1. Technical Field
The present invention is directed toward closure locks and latches, and more particularly toward locks and latches for sliding patio doors.
2. Background Art
Patio doors are, of course, well known in the art, typically having a stationary door and a sliding door which allows entry into and exit out of the home. It is particularly desirable that such doors have a maximum amount of glass so as to provide the open feeling to the home which is sought in homes having such doors.
Commonly, such doors have been provided with a simple lock mechanism which includes a finger which grasps a keeper on the door frame when locked by an operator inside the home. While such locks provide some security, they can relatively easily be opened by an intruder by simply drilling into the housing of the lock and moving the finger free of the keeper.
Further, in some door lock structures, multipoint locking and latching mechanism are used to increase the security of the locking and latching. With such structures, maintaining a proper inventory of different components to allow for many different types of possible installations can be costly. Further, as a practical matter, requiring different components for different installations can result in costly mistakes and/or delays when the wrong components are supplied to a site.
Still further, installation of multipoint locking and latching mechanisms is significantly more difficult than with single latch points, as the difficulty in properly mounting the latch members to the door and the keepers to the frame, with each being properly aligned with the other, is multiplied. Of course, if installation is not done properly, the latch members may not be properly aligned and therefore may not properly latch when the door is closed. When that occurs with even just one of multiple point latches, a potential intruder may be able to gain access between the door and the frame to be able to manipulate the properly latched latch members and thereby defeat whatever security the door was intended to provide. When such misalignment occurs laterally, that is when the keeper and the latch member are in line but do not come close enough to latch together when the door is closed, as can occur if the door is not properly aligned in the frame, that failure may not be readily apparent to the home dweller who will therefore dangerously assume that they are more secure than they really are.
In addition, when such doors are closed without being locked, it is often not readily apparent whether the doors have been completely shut, or when they are slammed shut, they can rebound slightly to leave an open gap. In either event, the door does not serve as a good seal against hear (or air conditioning) loss, and further does not act as a barrier against entry of dirt, water, and insects into the home. In some instances, the door can be unintentionally gapped open enough that the locking finger will miss the keeper when seemingly locked, thereby providing the homeowner with a dangerous false sense of security.
Of course, patio doors are often used in environments which are particularly corrosive (such as in seaside dwellings), and corrosion can deteriorate the physical stability of the structure, as well as interfere with smooth operation of moving parts as is typically desired over the long expected life of such structures. For example, with multipoint locks in the prior art, a tie bar has typically been provided to connect spaced latch members, with the tie bar being guided for movement longitudinally to move the latch members between latching and unlatching positions. If the tie bar deteriorates, it will typically not move as smoothly as desired since its smooth sides will become rough and/or distorted.
Further, guides for tie bar movement which have been provided heretofore have also tended to deteriorate over time which can also result in binding. For example, a typical structure which has been used heretofore has been cylindrical or square guides fixed by a single centrally disposed pin, such as a rivet, where the guides ride in longitudinal slots in the tie bar. However, cylindrical pins have a very small, essentially tangential, surface area cooperating with the tie bar slot, which initially may tend to reduce whatever minimal frictional contact exists between the two components, but also tends to highly concentrate the stresses and wear over a very small area, with the result being that a significant amount of looseness can develop over the years with resulting degradation in the smooth and reliable operation of the structure. While square guides have also been used and therefore tend to spread out the area of contact with the tie bar, such square guides are also susceptible to twisting about their mounting rivet and therefore can themselves cause binding or otherwise wear down unevenly due to stress concentrations occurring at points when the guides are twisted.
Of course, smooth operation of moving parts can also be inhibited by binding of components confined in a very tight space, a particular problem when a structure such as a patio door latch must be very tightly and reliable mounted to a very limited space available in a door.
One patio door structure which has been used is shown in U.S. Pat. No. 4,362,328. This structure provides a secure lock for patio doors, but does not prevent the problems which can be encountered when the door is intentionally left unlocked--namely, the presence of unintentional gaps when closing the door through which heat and air conditioning can be lost and through which dirt, water and insects can enter the home.
Another patio door structure which has been used is shown in U.S. Pat. No. 4,973,091, which includes a lock and latch mechanism actuated by a slightly pivotable handle which addresses a few of the above discussed problems in the prior art.
The present invention is directed toward overcoming one or more of the problems set forth above.